Method and system of extending battery life of a wireless microphone unit

ABSTRACT

A method of extending battery life of a wireless microphone unit includes muting the wireless microphone unit responsive to a mute signal from a base station unit, transmitting, by the wireless microphone unit, compressed muted audio data, wherein the compressed muted audio data is compressed via a first compression scheme, determining, by the wireless microphone unit, whether an unmute signal has been received from the base station unit, and responsive to a determination that the unmute signal has been received, unmuting the wireless microphone unit. The method further includes discontinuing transmission of the compressed muted audio data and transmitting compressed audio data via a second compression scheme, wherein the first transmitting step causes the wireless microphone unit to consume less power per unit of transmission time than the second transmitting step.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/224,100, filed on Mar. 25, 2014. U.S. patent application Ser. No.14/224,100 is a continuation of U.S. patent application Ser. No.12/509,939, filed on Jul. 27, 2009. U.S. patent application Ser. No.12/509,939 claims priority from U.S. Provisional Patent Application No.61/083,919, filed on Jul. 26, 2008. U.S. patent application Ser. No.14/224,100, U.S. patent application Ser. No. 12/509,939, and U.S.Provisional Patent Application No. 61/083,919 are incorporated herein byreference.

BACKGROUND

Technical Field

This patent application relates generally to microphones, and inparticular, to systems and methods for extending battery life of awireless microphone unit by incorporating data compression and muting ofthe microphone.

History of Related Art

Wireless microphones are used in many fields of endeavor today. Onetypical application of wireless microphones is in law enforcement. Atypical wireless microphone unit includes a microphone and a transmitterthat is used to transmit signals representing sounds detected by themicrophone. In a typical arrangement, a vehicle of a law-enforcementofficer includes a base station that is operable to communicatewirelessly with the wireless microphone unit.

Because the wireless microphone unit is wireless, it is necessary forthe wireless microphone unit to also include a battery. While batterytechnology has improved greatly in recent years, demands of transmissionby the wireless microphone unit in combination with unpredictable shiftlengths of law-enforcement officers can, in some circumstances, causelife of the battery incorporated into the wireless microphone unit to beexceeded.

SUMMARY OF THE INVENTION

A method of extending battery life of a wireless microphone unit. Themethod includes muting the wireless microphone unit responsive to a mutesignal from a base station unit, transmitting, by the wirelessmicrophone unit, compressed muted audio data, wherein the compressedmuted audio data is compressed via a first compression scheme,determining, by the wireless microphone unit, whether an unmute signalhas been received from the base station unit, and responsive to adetermination that the unmute signal has been received, unmuting thewireless microphone unit. The method further includes discontinuingtransmission of the compressed muted audio data and transmittingcompressed audio data via a second compression scheme, wherein firsttransmitting step causes the wireless microphone unit to consume lesspower per unit of transmission time than the second transmitting step.

A method of extending battery life of a wireless microphone unit. Themethod includes muting the wireless microphone unit responsive to a mutesignal from a base station unit and transmitting, by the wirelessmicrophone unit, run-length-encoded muted audio data. The method furtherincludes determining, by the wireless microphone unit, whether an unmutesignal has been received from the base station unit and responsive to adetermination that the unmute signal has been received, unmuting thewireless microphone unit.

An article of manufacture for extending battery life of a wirelessmicrophone unit, the article of manufacture includes at least onecomputer readable medium and processor instructions contained on atleast one computer readable medium, the processor instructionsconfigured to be readable from the at least one computer readable mediumby at least one processor and thereby cause the at least one processorto operate as to perform the steps of muting the wireless microphoneunit responsive to a mute signal from a base station unit, transmitting,by the wireless microphone unit, compressed muted audio data, whereinthe compressed muted audio data is compressed via a first compressionscheme, determining, by the wireless microphone unit, whether an unmutesignal has been received from the base station unit, responsive to adetermination that the unmute signal has been received, unmuting thewireless microphone unit, discontinuing transmission of the compressedmuted audio data and transmitting compressed audio data via a secondcompression scheme, wherein first transmitting step causes the wirelessmicrophone unit to consume less power per unit of transmission time thanthe second transmitting step.

An article of manufacture for extending battery life of a wirelessmicrophone unit, the article of manufacture includes at least onecomputer readable medium and processor instructions contained on atleast one computer readable medium, the processor instructionsconfigured to be readable from the at least one computer readable mediumby at least one processor and thereby cause the at least one processorto operate as to perform the steps of muting the wireless microphoneunit responsive to a mute signal from a base station unit, transmitting,by the wireless microphone unit, run-length-encoded muted audio data,determining, by the wireless microphone unit, whether an unmute signalhas been received from the base station unit and responsive to adetermination that the unmute signal has been received, unmuting thewireless microphone unit.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the method and system of the presentinvention may be obtained by reference to the following DetailedDescription when taken in conjunction with the accompanying Drawingswherein:

FIG. 1A is a block diagram illustrating communication between a wirelessmicrophone unit and a base station unit;

FIG. 1B is a flow diagram illustrating an exemplary process ofmute/unmute control of a wireless microphone unit;

FIG. 2 is a flow diagram illustrating an exemplary process for operationof a wireless microphone unit; and

FIG. 3 is a detailed block diagram of an exemplary wireless microphoneunit.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS OF THE INVENTION

Various embodiments of the present invention will now be described morefully with reference to the accompanying drawings. The invention may,however, be embodied in many different forms and should not be construedas limited to the embodiments set forth herein; rather, the embodimentsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the invention to those skilled in theart.

FIG. 1A is a block diagram illustrating communication between a wirelessmicrophone unit 12 and a base station unit 16. In a typical embodiment,the wireless microphone unit 12 includes a sound pickup device 14. In atypical embodiment, the sound pickup device 14 may be, for example, amicrophone. The sound pickup device 14 is coupled to a transmit/receive(TX/RX) unit 13 and an antenna 15 is coupled to the TX/RX unit 13. Inlaw-enforcement applications, according to a typical embodiment, thewireless microphone unit 12 may be attached to the person of alaw-enforcement officer. The wireless microphone unit 12 is operable toallow activities of the officer and interactions of the officer withother individuals to be detected by the wireless microphone unit 12 andtransmitted to another location for review and/or recording. In atypical arrangement, a vehicle of the law-enforcement officer includesthe base station unit 16, which is operable to communicate wirelesslywith the wireless microphone unit 12. In some systems, the base stationunit 16 may be, for example, a digital video recorder (DVR), a harddrive, a VHS system, or some other recording device that may be used,among other things, to record data received by the base station unit 16from the wireless microphone unit 12.

Some wireless microphone units are configured to change between astandby mode in which the wireless microphone unit does not transmit andan active mode in which the wireless microphone unit transmits. Thissolution represents an effort to take advantage of the general principlethat a typical wireless microphone unit uses less power and, therefore,discharges its battery more slowly, when the wireless microphone unit isnot transmitting relative to when the wireless microphone unit istransmitting.

However, in some circumstances, it is preferable that the wirelessmicrophone unit not enter into a standby mode in which transmissions bythe wireless microphone unit do not occur. In various embodiments,battery life of the wireless microphone unit 12 may be extended byincorporating data compression and muting of the sound pickup device 14of the wireless microphone unit 12. In a typical embodiment, the soundpickup device 14 is muted via, for example, analog mute circuitry ordigital mute circuitry. One type of data compression that may be used invarious embodiments of the invention is run-length encoding (RLE). RLEis a form of data compression in which a run of data (i.e., a sequencein which the same data value occurs in many consecutive data elements)is stored as a single data value and count, rather than as the originalrun of data. RLE is typically more useful on data that contain many suchruns, such as, for example, relatively simply graphic images such asicons, line drawings, and animations. RLE is typically not recommendedfor use with data that do not have many runs, as RLE could in such casespotentially double the size of the data being encoded.

In a typical embodiment, the wireless microphone unit 12 is responsiveto a signal to mute the sound pickup device 14 of the wirelessmicrophone unit 12. In response to such a signal, the wirelessmicrophone unit 12 mutes the sound pickup device 14. As a result, nosound or signals representative thereof are detected by the TX/RX unit13 or another component of the wireless microphone unit 12, resulting inone or more strings, for example, of zeros, which strings of zerosrepresent silence (i.e., no sound). In a typical embodiment, when thesound pickup device 14 has been muted, data transmitted by the wirelessmicrophone unit 12 defaults to zero. RLE of the resultant very longstring of zeros causes compression of the zeros into a relatively shortstring of data (e.g., two bytes) so that transmission of the detectedsilence is shorter in time and more energy efficient than ifuncompressed data representing silence were not so compressed.

In a typical law-enforcement application, it is desirable to controlmuting of the wireless microphone unit 12 remotely from the base stationunit 16 located, for example, in the law-enforcement vehicle. One way inwhich such remote muting can be implemented is responsive to recordingof video, for example, onto a DVR, VHS, hard drive, or other storagemedia such as, for example, a solid state memory. In such anarrangement, events deemed not important enough to record video of arealso considered not important enough to record audio of; therefore, insuch embodiments, the wireless microphone unit 12 is muted responsive toa signal from the DVR or other video-recording device that is part ofthe base station in the law-enforcement vehicle and, during these times,power usage by the wireless microphone unit 12 is minimized, whichcauses battery life to be extended. However, muting of the sound pickupdevice 14 may be triggered by other events as desired.

FIG. 1B is a flow diagram illustrating an exemplary process ofmute/unmute control of the wireless microphone unit 12 by the basestation unit 16, which, as discussed above, may include a DVR device. Aprocess 100 begins at step 102. From step 102, execution proceeds tostep 104. At step 104, a determination is made whether the DVR device ofthe base station unit 16 is recording video. Those having skill in theart will appreciate that principles of the invention may be appliedwhether a DVR-based recording device or other type of recording deviceis used and also may be applied regardless of whether the presence ofvideo recording is the triggering event as described hereinbelowrelative to the process 100.

Referring again to FIG. 1B, from step 104, if it is determined that theDVR device is recording, execution proceeds to step 106. At step 106,the base station unit 16 sends an unmute signal to the wirelessmicrophone unit 12. From step 106, execution proceeds to step 108. If,however, at step 104, it is determined that the DVR device is notrecording, execution returns to step 104.

At step 108, a determination is made whether the DVR device has stoppedrecording. If, at step 108, it is determined that the DVR device has notstopped recording, execution returns to step 108. However, if at step108 it is determined that the DVR device has stopped recording,execution proceeds to step 110. At step 110, an unmute signal is sent tothe wireless microphone unit 12. From step 110, execution proceeds tostep 104. It is thus apparent that the base station unit 16 sends anunmute signal responsive to the DVR device recording video and sends amute signal responsive to the DVR device recording no longer occurring.

FIG. 2 is a flow diagram illustrating an exemplary process for operationof the wireless microphone unit 12 responsive, for example, to mute andunmute signals such as those illustrated in FIG. 1A. Awireless-microphone-unit operation process 200 begins at step 202. Fromstep 202, execution proceeds to step 204. At step 204, the wirelessmicrophone unit 12 begins transmitting. From step 204, executionproceeds to step 206. At step 206, the wireless microphone unit 12 mutesthe sound pickup device 14. From step 206, execution proceeds to step208, at which step muted audio detected by the wireless microphone unit12 (i.e., silence) is compressed using a first data-compression scheme.In a typical embodiment, the first data-compression scheme involvesrun-length encoding the muted audio by the wireless microphone unit 12.As noted above, run-length encoding of data representing silence resultsin extremely short transmissions and improved energy efficiency of thewireless microphone unit 12. In addition, run-length encoding of datarepresenting silence typically results in less power consumption perunit of transmission time, resulting in extended battery life of thewireless microphone unit 12.

From step 208, execution proceeds to step 210. At step 210, adetermination is made as to whether an unmute signal has been received.If, at step 210, no unmute signal has been received, execution returnsto step 210. If, however, an unmute signal has been received at step210, execution proceeds to step 212. At step 212, the sound pickupdevice 14 of the wireless microphone unit 12 is unmuted.

At step 213, data is compressed using a second data-compression scheme.In some embodiments, the second data-compression scheme may be utilizedduring at least part of the time that the sound pickup device 14 of thewireless microphone unit 12 is unmuted. The second data-compressionscheme may include, for example, one or more of AAC, MP3, and DSS.Compression of data utilizing the second data-compression schemetypically causes the wireless microphone unit 12 to consume more powerper unit of transmission time than when the first data-compressionscheme disclosed above is used. In other embodiments, no datacompression is used during the time that the wireless microphone unit 12is unmuted.

From step 213, execution proceeds to step 214. At step 214, adetermination is made whether a mute signal has been received. If a mutesignal has not been received, execution returns to step 214. However, ifa mute signal has been received, execution returns to step 206.

Those having skill in the art will appreciate that FIGS. 1A-2 describejust one of a number of potential implementation modes for thecombination of run-length encoding and muting of the sound pickup device14 of the wireless microphone unit 12 and that a number of differentimplementation modes may be utilized without departing from principlesof the invention. In various embodiments of the invention, the wirelessmicrophone unit 12 never enters into a standby mode in which thewireless microphone unit 12 is powered up and operational but nottransmitting audio (i.e., sounds or silence). In another operationalmode from the one illustrated in FIGS. 1A-2, for example, the wirelessmicrophone unit 12 may monitor the base station unit 16 to determinewhether a video recording or some other event is occurring and mute orunmute responsive thereto.

FIG. 3 is a detailed block diagram of the wireless microphone unit 12.The wireless microphone unit 12 includes the sound pickup device 14. Ina typical embodiment, the sound pickup device 14 may be, for example, amicrophone. The sound pickup device 14 is coupled to thetransmit/receive (TX/RX) unit 13 via circuitry 302. The wirelessmicrophone unit 12 is operable to convert sound to digital data anddeliver the digital data to the TX/RX unit 13. The circuitry 302includes a pre-amplifier 304, analog mute circuitry 306, ananalog-to-digital converter 308, an AND gate 310, digital mute circuitry312 comprising a NOR gate, a first compression block 314, and a secondcompression block 316.

The pre-amplifier 304 is operable to amplify an analog sound signal fromthe sound pickup device 14 to obtain an amplified analog sound signal S₁that is input to the analog-to-digital converter 308. Theanalog-to-digital converter 308 is operable to convert the analog soundsignal S₁ to a digital signal S₂. The digital signal S₂ is input toeither or both of the first encoding block 314 and the second encodingblock 316. It will be apparent that the encoding performed by the blocks314 and 316 may be accomplished by hardware or software. In variousembodiments, battery life of the wireless microphone unit 12 may beextended by incorporating data compression and muting of the soundpickup device 14 of the wireless microphone unit 12.

In a typical embodiment, the sound pickup device 14 is muted via, forexample, the analog mute circuitry 306 and/or the digital mute circuitry312. Audio detected by the wireless microphone unit 12 that has beenmuted (i.e., silence) is, for example, compressed using a firstdata-compression scheme by the first encoding block 314 and/or thesecond encoding block 316. In a typical embodiment, the firstdata-compression scheme involves run-length encoding the muted audio. Asnoted above, run-length encoding of data representing silence results inextremely short transmissions and improved energy efficiency of thewireless microphone unit 12. In addition, run-length encoding of datarepresenting silence typically results in less power consumption whichresults in extended battery life of the wireless microphone unit 12.Those having skill in the art will appreciate that FIG. 3 illustrates anexemplary implementation of circuitry 302 coupling the sound pickupdevice 14 to the transmit/receive (TX/RX). It will be understood thatthe circuitry 302 is not limited to the embodiment disclosed, but iscapable of numerous additions, rearrangements, modifications andsubstitutions without departing from the spirit of the invention as setforth herein.

Although various embodiments of the method and system of the presentinvention have been illustrated in the accompanying Drawings anddescribed in the foregoing Detailed Description, it will be understoodthat the invention is not limited to the embodiments disclosed, but iscapable of numerous rearrangements, modifications and substitutionswithout departing from the spirit of the invention as set forth herein.

What is claimed is:
 1. A method of extending battery life of amicrophone unit, the method comprising: muting the microphone unitresponsive to a mute signal from a base station unit; transmitting, bythe microphone unit, compressed muted audio data; determining, by themicrophone unit, whether an unmute signal has been received from thebase station unit; responsive to a determination that the unmute signalhas been received, unmuting the microphone unit; and wherein the basestation unit comprises a recording device configured to record thecompressed muted audio data.
 2. The method according to claim 1,wherein, responsive to the muting step, the muted audio data defaults tozero.
 3. The method according to claim 1, wherein the compressed mutedaudio data comprises at least one string of zeros compressed into ashort string of data.
 4. The method according to claim 3, wherein the atleast one string of zeros represents silence.
 5. The method according toclaim 1, wherein, responsive to the muting step, audio data representingsilence is received by a transmit/receive unit of the microphone unit.6. The method according to claim 1, wherein, responsive to the unmutingstep, the microphone unit performs the following steps: discontinuingtransmission of the compressed muted audio data; and transmittingcompressed audio data utilizing at least one of Digital Speech Standard(DSS), Advanced Audio Coding (AAC), and MP3.
 7. The method according toclaim 1, wherein, responsive to the unmuting step, the microphone unitperforms the following steps: discontinuing transmission of thecompressed muted audio data; and transmitting uncompressed audio data.8. The method according to claim 1, wherein the muting step comprisesdisconnecting a sound pickup device of the microphone unit from atransmit/receive unit of the microphone unit.
 9. The method according toclaim 1, wherein the muting step comprises muting the microphone unitutilizing analog mute circuitry.
 10. The method according to claim 1,wherein the muting step comprises muting the microphone unit utilizingdigital mute circuitry.
 11. The method according to any of claim 1,wherein the steps are performed in the order listed.
 12. The methodaccording to any of claim 1, wherein the microphone unit comprises awireless microphone unit.
 13. The method according to any of claim 1,wherein the compressed muted audio data comprises run-length-encodedmuted audio data.
 14. An article of manufacture for extending batterylife of a microphone unit, the article of manufacture comprising: atleast one non-transitory computer readable medium; processorinstructions contained on the at least one non-transitory computerreadable medium, the processor instructions configured to be readablefrom the at least one non-transitory computer readable medium by atleast one processor and thereby cause the at least one processor tooperate as to perform the following steps: muting the microphone unitresponsive to a mute signal from a base station unit; transmitting, bythe microphone unit, compressed muted audio data; determining, by themicrophone unit, whether an unmute signal has been received from thebase station unit; responsive to a determination that the unmute signalhas been received, unmuting the microphone unit; and wherein the basestation unit comprises a recording device configured to record thecompressed muted audio data.
 15. The article of manufacture according toany of claim 14, wherein the microphone unit comprises a wirelessmicrophone unit.
 16. The article of manufacture according to claim 14,wherein the compressed muted audio data comprises run-length-encodedmuted audio data.
 17. A system for extending battery life of amicrophone unit, the system comprising: a microphone unit; a basestation unit configured to wirelessly communicate with the microphoneunit; wherein the microphone unit is configured to: enter a mute moderesponsive to receiving a mute signal from a base station unit; transmitcompressed muted audio data; determine whether an unmute signal has beenreceived from the base station unit; responsive to a determination thatthe unmute signal has been received, unmute the microphone unit; andwherein the base station unit comprises a recording device configured torecord the compressed muted audio data.